Rule No. 4

A second complication is that while some commodities have risen in price along with inflation since the Industrial Revolution, they have become much cheaper in some other economically significant term, such as time.

In 1870 a round-trip, second-class passage from New York to London could be purchased for about $150. This price would have been in the reach of many middle-class families. But in 1870 the passage took about ten days in each direction, and paid vacations were unknown. Therefore, while many Americans in 1870 could afford the money cost of a trip to England, very few could afford what it cost in time. Today the Atlantic can be crossed in a few hours and paid vacations are the norm. Thanks to jet travel and more enlightened labor policies, Europe now swarms with American tourists (and vice versa).